Two wheel device for positve feeding of yarn to knitting machine

ABSTRACT

A device for positive feeding of yarn to a knitting machine, which device has independently rotatable first and second wheels disposed axially closely adjacent and individually supported for rotation about first and second axes which extend in the same general direction but are slightly inclined relative to one another. First and second feeding tapes are drivingly engaged with the first and second wheels respectively. A shiftable yarn guiding element feeds a yarn therethrough to a selected one of the wheels, with the guiding element being shiftable between first and second positions to enable the yarn to be positively fed by the first and second wheels respectively.

FIELD OF THE INVENTION

The present invention relates to a device for the positive feeding ofyarn to a knitting machine, preferably a circular knitting machine, forknitting pieces of goods with a ready-made-up length, in which everyknitted piece has portions with a different stitch length or knittingstructure.

BACKGROUND OF THE INVENTION

The invention is based on a device which has a yarn feeding wheel whichis freely journalled on a fixed shaft in the device, and a feeding tapesynchronously driven by the knitting machine, which tape is adapted torun over a part of the periphery of said yarn feeding wheel with adesired speed. A yarn control element associated with the yarn feedingwheel is also arranged to bring the yarn into engagement with the yarnfeeding wheel and the yarn feeding tape, co-acting therewith for thepositive feeding of the yarn to the knitting place with said desiredspeed and also to guide the yarn out of this engagement into a positionoutside the feeding tape on the yarn feeding wheel to interrupt thepositive feeding thereof.

In the case of knitting pieces of goods with ready-made-up lengths, andalso in other connections, there is a requirement for being able topositively feed a yarn in one and the same knitting system with at leasttwo different speeds during the various parts of the knitting cycle forsuch goods. For example, an instance can be mentioned where one knits a"pullover", where the short, lower-most section in the form of a "waistrib" should be knitted with a first positive yarn speed for generating afirst portion in the goods with a first stitch size and character.Immediately thereafter, the long breast and belly section ("bodysection") is to be knitted with a second, positive yarn speed forgenerating a second portion in the goods with a second stitch size andcharacter. This case is described in detail in the British PatentSpecification No. 1.246.625 (Hosiery and Allied Trade ResearchAssociation, Nottingham), which also shows a yarn feeding deviceconsisting of so-called "nip rollers" which enables the desired positivefeeding of a yarn with two different speeds in one and the same knittingsystem during various parts of the knitting cycle.

GB-A-2 109 825 already discloses a device for the positive feeding ofyarn to a knitting machine. The prior art device comprises two feedingwheels of different diameter which are caused to rotate at differentrotational speeds. A number of turns of the yarn to be fed to theknitting machine are wound around the second wheel and a cone andfurther around the first wheel where the yarn is engaged by the feedingtape. Depending on the yarn tension, the yarn comes into and out ofengagement with the feeding tape. Hence, the tension of the yarn can becontrolled as desired. However, this prior art apparatus is not adaptedfor carrying out a positive feeding of the yarn at two different,clearly defined, speeds.

The object of the present invention is to accomplish a yarn feedingdevice adapted for a selective positive feeding of the yarn at differentspeeds having a less complicated structure than that of the prior artdevices.

In accordance with the present invention, this object is achieved by adevice.

A further object of the present invention is to ensure a permanentlycorrect positioning of the feeding tapes on the two yarn feeding wheels,namely that the feeding tape on the respective yarn feeding wheel shouldalways run over the wheel at its edge remote from the crossing betweenthe two wheels. According to one embodiment of the invention, thisobject is accomplished by the rotation axes of the two yarn feedingwheels forming a small, acute angle, with each axis being inclined at asmaller angle from a line perpendicular, to the normal planes ofmovement for the two feeding tapes. This geometrical relationship ispreferably accomplished by the journalling position for the further yarnfeeding wheel on the fixed shaft consisting of a hub portion, the centreaxis of which forms a small acute, "positive" angle to the centre lineof the fixed shaft. The first yarn feeding wheel is journalled on a hubportion concentrically arranged with the centre line of the fixed shaft.Moreover, the whole yarn feeding device is arranged to be mounted on asupport ring extending horizontally above the knitting machine andparallel to the feeding tapes in a conventional manner such that thecentre line of the fixed shaft on which the two yarn feeding wheels arejournalled, forms a small, acute, "negative" angle absolute relative toa line perpendicular to the normal planes of movement for the twofeeding tapes. The "negative" angle has a smaller absolute valve thansaid "positive" angle.

Another object of the present invention is to facilitate the alterationof the speed of the yarn. Therefore, according to the invention, thedevice has, in one embodiment, an annular guiding flange fixed to therim of the first yarn feeding wheel facing the further yarn feedingwheel and extending axially out over a small piece of the further yarnfeeding wheel, which flange is adapted to enable the smooth sliding ofthe yarn over it from its position on the first yarn feeding wheel intoa position on the further yarn feeding wheel, and vice versa.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the device according to the invention isdescribed below with reference to the drawings, wherein

FIGS. 1 and 2 show two different views of this embodiment;

FIG. 3 shows the same embodiment where vital parts in the device areshown in longitudinal sections;

FIG. 4 shows the actuation means for the yarn control element in a moredetailed form.

DETAILED DESCRIPTION

As shown at FIGS. 1 and 2, a knitting machine has a support ring 1 knownper se, which is arranged to carry a number of identical yarn feedingdevices. The respective feeding devices are located above the respectiveknitting places or yarn intakes of the circular knitting machine (notshown here), whereby said number corresponds to the number of knittingsystems in the machine. Every yarn feeding device has a hook-formedattachment part 2a on the housing 2 which is intended for fitting thedevice to the support ring 1 in which a lock screw 3 is arranged forfixing the yarn feeding device on the support ring 1. On said supportring 1 a flat, electrical cable 4 comprising five electrical conductorswhich are principally the same as is shown in the Applicant's ownEuropean Patent Application No. 821101173.0 (publication No. 78 550) areconnected to an electrical, preferably micro-processor-based controlunit centrally arranged in the knitting machine. Two of the saidconductors (not shown here) are connections connected to respective oneof two electro-magnets EM₁ and EM₂ fixed in the housing 2 of the yarnfeeding device, which electro-magnets are more closely shown in FIG. 4.

In supporting plate 5 projecting from the housing 2 a vertical, fixed(unrotatable) shaft 6 is attached. A first yarn feeding wheel FW₁ is bymeans of a ball bearing 7 (see FIG. 3) pivotably journalled on a hubportion 8 on the shaft 6 concentrically arranged with the centre line 6'of the shaft 6. A further yarn feeding wheel FW₂ via a furtherball-bearing 9 is rotatably journalled on a second hub portion 10 on theshaft 6, whereby the centre line 10' of said second hub portion 10 formsa 2° angle to the centre line 6' of the shaft 6.

First and second feeding tapes FT₁, FT₂ are arranged to run over a partof the periphery of the respective yarn feeding wheels with first andsecond different linear speed v₁, v₂, synchronous with the drive of theknitting machine. Said speeds correspond to the positive feed speedswith which a yarn Y₁,2 from a yarn supply spool is, according to thepresent invention, fed by means of the yarn feeding device down to theworking needles in the knitting machine as mentioned above so as to knitthe "waist rib portion" or the "belly and breast section" in thepullover. The feeding tapes FT₁ and FT₂ are driven from the drive systemof the knitting machine via a respective so-called quality adjustmentpulley with an adjustable drive diameter in order to achieve the desiredspeeds v₁, v₂ synchronous with the needle cylinder speed.

At point P in the housing 2 in the yarn feeding device, a yarn guidingarm 11 is pivotally journalled, which has a horizontal bearing part 11aand a guiding part 11b essentially perpendicular thereto which, at itsfree end, carries a yarn guiding eyelet 11c for guiding the position ofthe in-coming yarn Y₁,2 in the yarn feeding device.

The yarn guiding arm 11 is an arrangement of two electro-magnets EM₁ andEM₂ and a common return spring RS adapted to be able to take one ofthree possible positions through a control command from theabove-mentioned, preferably a micro-processor-based electronic controlunit, centrally arranged in the knitting machine via two of theconductors in the flat cable 4.

When none of the electro-magnets are actuated, the yarn guiding arm 11will take the "neutral position" shown in FIGS. 1, 2 and 4 through theinfluence of the return spring RS. The yarn Y₁,2 running through theyarn guiding eyelet 11c will be in a position outside the feeding tapeFT₁ on the yarn feeding wheel FW₁ in which it will not be subject to anypositive feed. The working needles in the machine will, themselves, pullthe yarn Y₁,2 from the yarn supply spool via the wheel FW₁ rotating withthe speed v₁.

During actuation of the lower electro-magnet EM₁, the yarn guiding arm11 will pivot in a clockwise direction under the influence of themovement of the armature 12 so that the yarn Y₁,2 comes into engagementbetween the feeding tape FT₁ and the yarn feeding wheel FW₁, whereby theyarn Y₁,2 will be subjected to positive feeding with the speed v₁ of thefeeding tape FT₁.

During de-actuation of the lower electro-magnet EM₁ and directlyfollowing actuation of the upper electro-magnet EM₂, the yarn guidingarm 11 swivels in an anti-clockwise direction, whereby the yarn Y₁,2leaves its engagement between the feeding tape FT₁ and the wheel FW₁ viaits "neutral position" shown in the Figures. This is utilized for makingthe first course of stitches in the goods to be knitted and, duringadjustment and re-adjustment work in the machine, the yarn is movedover, under the influence of the movement of the armature 13 into ananalogous engagement below the further feeding tape FT₂ so that,instead, the yarn Y₁,2 will be subjected to positive feeding with thespeed v₂ of the feeding tape FT₂.

By means of an annular guiding flange 14 attached to the lower rim ofthe wheel FW₁ and preferably made of highly polished aluminium, whichflange extends axially out over a small piece of the wheel FW₂, thewandering of the yarn Y₁,2 from the one yarn feeding wheel to the other,and vice versa, will be facilitated.

When the yarn is drivingly engaged between the tape FT₁ and the wheelFW₁, then the yarn guiding eyelet 11c will be in its uppermost position(that is, displaced upwardly from the neutral position shown in FIG. 2).However, when the yarn is to be fed by the other feeding wheel FW₂, thenthe arm 11 is pivotally swung downwardly so that the yarn guiding eyelet11c is moved downwardly through the neutral position into a lowermostposition wherein it is disposed adjacent but spaced radially outwardlyfrom the wheel FW₂. During this downward movement of the eyelet 11c theyarn is moved downwardly out from beneath the tape FT₁ and is slidablymoved downwardly across the guiding flange 14 into engagement with thelower feeding wheel FW₂, whereupon the yarn is engaged between the tapeFT₂ and the wheel FW₂. This downward displacement of the yarn isfacilitated by the beveled or chamfered surface provided adjacent theupper edge of the annular guiding flange 14.

When the yarn is to be again moved upwardly for re-engagement with thetop feed wheel FW₁, the eyelet 11c is shifted upwardly through theneutral position back into its uppermost position, and this results in aportion of yarn extending from the eyelet 11c downwardly in inclinedrelationship across the edge of the guiding flange 14 into engagementbetween the driving tape FT₂ and the wheel FW₂. Due to the fact that theeyelet 11c is spaced radially outwardly a substantial distance from boththe wheels and the guiding flange 14, and is also displacedcircumferentially from the point where the tapes engage the respectivewheels, this hence enables the yarn portion which extends downstreamfrom the eyelet 11c to readily pass upwardly over the flange 14 when theeyelet 11c is moved upwardly. These relationships, coupled with themovement of the tape FT₂ and the associated movement of the wheel FW₂facilitate the upward movement of the yarn out of engagement with thetape FT₂ so that the yarn can again be displaced upwardly by the upwardmovement of the eyelet 11c for engagement between the tape FT₁ and thewheel FW₁.

As is apparent from FIG. 2, the whole yarn feeding device is mountedsuch with its attachment portion 2a onto the support ring 1, with whichthe two feeding tapes FT₁ and FT₂ are adapted to run parallel by meansof the previously mentioned quality wheels and guiding-rollers (notshown here). The centre line 6' of the fixed shaft 6 in the device formsa 1° "negative" angle to the normal of the planes of movement for thetwo feeding tapes. Due to this, it will be ensured that the feeding tapeFT₁ always runs over the wheel FW₁ adjacent its upper rim. As aconsequence of said "inclined" mounting of the yarn feeding device onthe support ring 1 and the previously mentioned angle of 2° between thecentre line 10' of the hub portion 10 on the wheel FW₂ and also to thecentre line 6' of the fixed shaft 6, said centre line 10' will form a 1°"positive" angle normal to the planes of movement for the two feedingtapes through which it is analogously ensured that the feeding tape FT₂will always run over the wheel FW₂ adjacent its lower rim.

The yarn feeding device comprises fixed guiding eyelets 15a, 15b and 15cfor the yarn and a pivotally journalled yarn tensioning arm 16 which isalso used for sensing the position of the yarn and for detecting a yarnbreakage condition. The pivotable yarn tensioning arm 16 is known per sein the art.

In the embodiment of the invention shown in the drawings, the yarnfeeding device also comprises a third yarn feeding wheel FW₃ which, likethe wheel FW₁, is concentrically journalled on the fixed shaft 6. Thewheel FW₃, with respect to the present invention, is irrelevant and,therefore, not described in more detail, co-acts with a feeding tape FT₃for the positive feeding of another yarn Y₃ which, during certain partsof the knitting cycle, is utilized as strengthening thread, as in theabove-described case, during the initial phase of knitting the"waist-rib" in the goods.

I claim:
 1. In a device for the positive feeding of yarn to a knittingmachine, including:a first freely rotatable yarn feeding wheel; a firstfeeding tape arranged to run over a part of the periphery of said firstyarn feeding wheel, which first feeding tape is driven at a first speedin synchronism with the operation of the knitting machine; a yarnguiding element adapted for selectively bringing the yarn intoengagement with said first yarn feeding wheel and said first feedingtape so as to positively feed tha yarn at the speed of the first feedingtape or bringing the yarn out of engagement with said first yarn feedingwheel for terminating the positive feeding of the yarn; and a secondyarn feeding wheel adapted to be rotated at a speed which is differentfrom the speed of the first yarn feeding wheel, the improvementcomprising: said second yarn feeding wheel being adapted to be rotatedindependent from said first yarn feeding wheel, a second feeding tapearranged to run over a part of the periphery of said second yarn feedingwheel, which second feeding tape is driven at a second speed differentfrom said first speed, said second speed being in synchronism with theoperation of the knitting machine, said second yarn feeding wheel beingarranged adjacent to said first yarn feeding wheel, the axes of saidyarn feeding wheels extending in approximately the same direction, andsaid yarn guiding element being adapted for selectively bringing saidyarn into engagement with said second yarn feeding wheel and said secondfeeding tape so as to positively feed the yarn at the speed of thesecond feeding tape or bringing the yarn out of engagement with saidsecond feeding tape for terminating said positive feeding, and formoving the yarn from one yarn feeding wheel to the other yarn feedingwheel and vice versa.
 2. Device as claimed in claim 1, whereintherotational axes of said first and second yarn feeding wheels areinclined with respect to each other so that the axes together form asmall acute angle, and the rotational axes of said first and second yarnfeeding wheels are arranged such that the respective ends of said yarnfeeding wheels remote from the respective other yarn feeding wheel areslightly inclined versus the normal plans of movement of said feedingtapes.
 3. Device as claimed in claim 2, whereinsaid second yarn feedingwheel is journalled at a hub portion of a fixed shaft, the centre axisof said hub portion forming said small acute angle together with thecentre line of the fixed shaft, said first yarn feeding wheel beingjournalled at a hub part concentrically arranged with said centre lineof said fixed shaft, and said yarn feeding device is adapted to bemounted on a support ring extending horizontally above the knittingmachine and in parallel to the feeding tapes such that the centre lineof the fixed shaft and a direction perpendicular to the plane ofmovement of the feeding tapes form a small acute angle having a smallerabsolute value than the small acute angle defined by the centre axis ofthe hub portion and the centre line of the fixed shaft.
 4. Device asclaimed in claim 1, includingan annular guiding flange fixed to a rim ofthe first yarn feeding wheel facing said second yarn feeding wheel,which flange slightly extends axially over said second yarn feedingwheel, which flange enables a smooth sliding of the yarn from the firstyarn feeding wheel to the second yarn feeding wheel and vice versa. 5.Device as claimed in claim 2, wherein: the rotational axis of said firstyarn feeding wheel is inclined at an angle of about 1° relative to aperpendicular to the normal plane of movement of said first feedingtape, the rotational axis of said second yarn feeding wheel is inclinedat an angle of about 1° relative to a perpendicular to the normal planeof movement of said second feeding tape, and the small acute angle asdefined by the rotational axes of said first and second yarn feedingwheels is about 2°, whereby the respective feeding tape tends todrivingly engage the respective yarn feeding wheel adjacent therespective axial end thereof which is remote from the other yarn feedingwheel.
 6. Decive as claimed in claim 5, wherein said yarn guidingelement is supported for shifting movement between first and secondpositions for respectively bringing the yarn into engagement with thefirst and second yarn feeding wheels, and actuator means for selectivelyeffecting shifting of said yarn guiding element between said first andsecond positions, said actuator means including first and secondelectromagnetic actuators for respectively shifting said yarn guidingelement into said first and second positions.
 7. Device as claimed inclaim 1, wherein said yarn guiding element is supported for shiftingmovement between first and second positions for respectively bringingthe yarn into engagement with the first and second yarn feeding wheels,and actuator means for selectively effecting shifting of said yarnguiding element between said first and second positions, said actuatormeans including first and second electromagnetic actuators forrespectively shifting said yarn guiding element into said first andsecond positions.
 8. A positive yarn feeding device adapted to bemounted on a supporting ring of a circular knitting machine,comprising:a support housing having means for permitting attachment tothe support ring; upright shaft means stationarily mounted on saidsupport housing; a first yarn feeding wheel freely rotatably supportedon said shaft means for rotation about a first axis which is generallyupright, and a first feeding tape arranged to run over a part of theperiphery of said first yarn feeding wheel for driving said first wheelat a first speed in synchronism with the operation of the knittingmachine; a second yarn feeding wheel freely rotatably supported on saidshaft means for rotation about a second axis which is generally upright,and a second feeding tape arranged to run over a part of the peripheryof said second yarn feeding wheel for driving said second wheel at asecond speed which is different from said first but which is insynchronism with the operation of the knitting machine; said secondwheel being disposed generally directly below and approximatelycoaxially aligned with said first wheel; p1 a yarn guiding element forselectively guiding a yarn into engagement with said first and secondfeeding wheels, said yarn guiding element being mounted on said supporthousing for shifting movement relative thereto between (1) a firstposition wherein it guides the yarn into engagement with the first yarnfeeding wheel and said first feeding tape so as to positively feed theyarn at said first speed and (2) a second position wherein it guides theyarn into engagement with said second feeding wheel and said secondfeeding tape so as to positively feed the yarn at said second speed; andactuator means mounted on said support housing for selectively shiftingsaid yarn guiding element between said first and second positions toeffect transfer of the yarn between said first and second feedingwheels.
 9. Device according to claim 8, wherein the first axis extendsat a first very small acute angle relative to a line which isperpendicular to the plane of movement of the first feeding tape so thatthe first feeding tape tends to engage the first feeding wheel adjacentthe upper axial end thereof, and wherein said second axis extends at asecond very small acute angle relative to a line perpendicular to theplane of movement of said second feeding tape so that the second feedingtape tends to engage the second feeding wheel adjacent the lower axialend thereof.
 10. Device according to claim 9, including an annular guideflange fixed to one of the adjacent axial ends of one feeding wheel andprojecting axially in surrounding relationship to the other of saidadjacent axial ends as defined on the other feeding wheel to permit theyarn to smoothly shift between said first and second feeding wheels inresponse to shifting of said guiding element between said first andsecond positions.
 11. Device according to claim 10, wherein the firstand second feeding tapes have generally parallel planes of movement, andsaid first and second axes extend on slightly inclined relationship toone another and define a third small acute angle therebetween whichequals the sum of said first and second acute angles.
 12. Deviceaccording to claim 11, wherein each of said first and second acuteangles is about 1°.
 13. Device according to claim 8, wherein saidactuator means includes electromagnetic means.
 14. Device according toclaim 8, wherein said yarn guiding element is movable into a thirdposition wherein the yarn is free of driving engagement with both ofsaid first and second yarn driving wheels, said third position beinglocated between said first and second positions.